Fresh-Resolvers

What the resolver list is

Fresh Resolvers is a list of DNS resolvers that is updated on an hourly basis. The README describes it as a list of hourly updated valid DNS resolvers. The project exists to give security tools a current set of working resolvers so that resolution during scans stays reliable. A resolver in this context is a DNS server that answers queries, and the list collects ones that have been checked rather than scraped blindly. The README states that the data comes from public-dns.info, specifically the nameservers.txt file published there. That source is a public catalog of open DNS resolvers, and Fresh Resolvers turns it into a curated, frequently refreshed list. The project is small and focused: it does not ship a resolver of its own, it aggregates and validates existing public ones. For a user running large subdomain enumeration, a stale or dead resolver slows the whole job, so an hourly refresh cycle keeps the working set current. The README keeps the description short and points to the validation tool and the consuming tools rather than explaining internals. The list is published to the repository on an hourly basis, which is the core promise of the project and the reason users subscribe to it instead of using a one time snapshot.

How resolvers are validated

The README explains the validation pipeline in one sentence. DNS Validator is used to validate DNS resolvers taken from public-dns.info, and the resulting list is pushed to this repository on an hourly basis. DNS Validator is a separate open source project that probes candidate resolvers and keeps only the ones that respond correctly, so the published list should contain working servers rather than random IP addresses. The source file is nameservers.txt from public-dns.info, which is a broad public index of resolvers. Fresh Resolvers depends on that index and on DNS Validator to filter it. The hourly push means the validation runs on a schedule, not by hand, and subscribers get a fresh file without running the validator themselves. The README does not describe the exact schedule script or the infrastructure that runs it, so the automation is not documented in the text, but the cadence is stated clearly as hourly. The project also gives a contact path: if the resolvers list has not updated for more than a day, the maintainer asks users to send a direct message on Twitter. That note tells a reader that the expected update window is at most roughly a day, and a longer gap is treated as a problem worth reporting.

Tools that use the list

The README names several tools that can consume the resolver list. It mentions shuffledns from Project Discovery, massdns from blechschmidt, and zdns from zmap as examples of tools that make use of resolvers. These are common in subdomain enumeration and DNS research, and a fresh resolver list helps them run at scale without hitting dead servers. shuffledns and massdns in particular resolve large wordlists of subdomains, where resolver quality directly affects speed and coverage. The README presents these as examples with an etc, meaning the list is not limited to them. Any tool that accepts a list of resolver addresses can point at the file. The project's value is therefore in supplying the input data, not in providing the scanning logic itself. By keeping the list current every hour, Fresh Resolvers reduces the chance that a long enumeration job stalls on broken resolvers. The README also thanks Codingo and Vortexau for creating DNS Validator, which is the tool that does the actual validation behind the list. A user who wants the same result locally can run DNS Validator directly against public-dns.info, but most will prefer to pull the already validated list from this repository on its hourly cycle. Keeping a local copy lets a team pin a known good revision, while the hourly upstream updates remain one git pull away whenever they want the newest resolvers.

Editorial conclusion

The list is validated with DNS Validator against public-dns.info and pushed hourly, and it can be used with shuffledns, massdns, and zdns. The README thanks Codingo and Vortexau for creating DNS Validator.